One type of ink-jet printing system has a printhead mounted to a carriage that is moved back and forth over a print media, such as paper. As the printhead passes over appropriate locations on the print media, a control system activates the printhead to eject ink drops onto the printing surface and form desired images and characters. To work properly, such printing systems must have a reliable supply of ink for the printhead.
One category of ink-jet printing system uses an ink supply that is mounted to and moves with the carriage. In some types, the ink supply is replaceable separately from the printhead. In others, the printhead and ink supply together form an integral unit that is replaced once the ink in the ink supply is depleted.
Another category of printing system uses ink supplies that are not located on the carriage. One type replenishes the printhead intermittently. The printhead will travel to a stationary reservoir periodically for replenishment. Another type, referred to as a replaceable off-axis ink supply, has a replaceable ink cartridge or container connected to the printhead by a fluid conduit. The ink cartridge has a fluid reservoir filled with ink and located within a housing. The reservoir has a fluid coupling mechanism for coupling the reservoir to the printing system so that ink may flow from the reservoir to the printhead. The reservoir is sometimes pressurized in some manner to provide a reliable high flow rate supply of ink to the printhead.
In the parent application to this application, application Ser. No. 08/785,580, a replaceable off-axis cartridge is described which has a memory device mounted to the housing. When inserted into the printing system station, an electrical connection between the printing system and the memory device is established. This electrical connection allows for the exchange of information between the printing system and the memory. The memory device stores information that is utilized by the printing system to ensure high print quality. This information is provided to the printing system automatically when the cartridge is mounted to the printing system. The exchange of information assures compatibility of the cartridge with the printing system. The stored information includes helpful information, such as the date when the cartridge was first installed on a printing system. This installation date can be used to deduce how long the cartridge has been installed and hence whether the ink contained in the cartridge may be beyond shelf life.
The stored information further prevents the use of the cartridge after it is depleted of ink. Operating a printing system when the reservoir has been depleted of ink can destroy the printhead. The memory devices concerned with this application are updated with data from the printhead concerning the amount of ink left in the reservoir as it is being used. When a new cartridge is installed, the printing system will read information from the memory device indicative of the reservoir volume. During usage, the printing system estimates ink usage and updates the memory device to indicate how much ink is left in the cartridge. When the ink is substantially depleted, this type of memory device can store data indicative of an out of ink condition. When substantially depleted of ink, these cartridges are typically discarded and a new cartridge along with a new memory device is installed.
The ink containers described in the parent application have fixed volumes of deliverable ink that have been provided for printing systems based generally on ink usage rate requirements of a particular user. However, printing systems users have a wide variety of ink usage rates that may change over time. For ink-jet printing system users who require relatively high ink usage rates, ink containers having these volumes require a relatively high ink container replacement rate. This can be especially disruptive for print jobs which are left to run overnight. Extended continuous use of printing systems causes ink containers to run out of ink during a print job. If the printing system does not shut down during an "ink out" condition, the printhead or the printing system itself may be permanently damaged.
For printing system users who require lower volumes of ink, a different set of problems is encountered if the ink volume is too large. The ink may surpass its shelf life prior to being utilized. Larger ink cartridges are more expensive and bulkier than smaller cartridges and may be cost prohibitive to small volume users. Thus, a need exists for providing adaptive ink supplies for the ink cartridge described in the parent application, so that ink containers having a variety of ink volumes may be utilized. The adaptive ink supplies should be still able to provide to the printing system the benefits of the memory device of the original equipment ink cartridge.